Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Black Widows

  1. Oct 12, 2005 #1
    My sister, whose pyscho about spiders, is *****ing about seeing a black widow. We live in Canada. She says she knows that it's black widow because it was red on the top. But it's their belly, not their top, that's supposed to be red right? (Although maybe I misunderstood her....maybe she saw the it belly-side-up....or something)

    Anyways I'd appreciate answers to this as soon as possible, especially if what she saw wasn't a black widow
  2. jcsd
  3. Oct 12, 2005 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Black widows have an hourglass-shaped red marking on their abdomen (yes, on their ventral side...what you probably mean by "belly"). There are other spiders that have red markings that are not black widows.

    Here's a site with information about black widow spiders, including their habitat ranges. http://members.tripod.com/~LouCaru/index-13.html
  4. Oct 12, 2005 #3
    They are in Canada, but only in 'secluded' sites, like the Desert that is in Alberta, in Dinosaur Provincial Park.
  5. Oct 12, 2005 #4
    They can also travel anywhere with shipments of fruit and veggies.
  6. Oct 12, 2005 #5


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    "Five recognized species" north of the U.S.-Mexican border --- all five can be found in SE Texas, plus possible additional species. Color ranges from "milk chocolate" thru black to a gun-metal blue-black --- the hour glass may be totally absent in some individuals, but not often. Juvenile imagoes often exhibit "racing stripes" on the dorsal surface of the abdomen in the form of red and/or white comic book lightning bolts; these are paired laterally and disappear at the rate of one or two pairs per molt (occasionally still visible on two yr. olds --- sparse food reducing the rate of maturation), but usually not present once the abdomen exceeds 6mm diameter.
    The level of aggression varies among individuals within species --- anything from the "timid retreat" to the full charge with raised front legs (usually an egg sac in the vicinity).
    Don't bother it, and it won't bother you --- keeps the bugs down.
  7. Oct 14, 2005 #6
    We get black widows every year, sometimes in the house even. They no longer freak me out. They are not aggressive towards people without provocation.

    I killed one two days ago - huge one - And I'm glad I saw your post because I forgot to finish off the egg sac and must go do that now.

    Edit: There. That's taken care of. And I forgot to second Moon bear's comment - the hourgalss is distinct and on the ventral (belly) side. The spiders are very shiny (not fuzzy) and make tangled webs and often hang upside down (thus allowing the "belly" and hourglass to face up.)
    Last edited: Oct 14, 2005
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Black Widows
  1. *Black Plants | (Replies: 3)

  2. Black Queen Hypothesis (Replies: 2)